Substituted naphtho(2,1-b)pyrylium perchlorates

ABSTRACT

NAPHTHOPYRYLIUM SALTS REPRESENTED BY THE FORMULA (1) :   (2-R1,3-R2-NAPHTHO(2,1-B)PYRYLIUM) A(-)   WHEREIN R1 IS SELECTED FROM THE GROUP CONSISTING OF, PALKYLSTYRYL IN WHICH THE ALKYL HAS 1 - 3 CARBON ATOMS, P-ALKOXYSTYRYL IN WHICH THE ALKYL HAS 1 - 3 CARBON ATOMS, 3,4-DIALKOXYSTYRYL IN WHICH THE ALKYL HAS 1 - 2 CARBON ATOMS, 3,4,5-TRIALKOXYSTYRYL IN WHICH THE ALKYL HAS 1-2 CARBON ATOMS, P-DIALKYLAMINOSTRYL IN WHICH THE ALKYL HAS 1-4 CARBON ATOMS, P-NITROSTYRYL, P-HALOGENOSTRYL, P-CARBOXYSTYRYL; R2 IS SELECTED FROM THE GROUP CONSISTING OF, P-ALKOXYPHENYL IN WHICH THE ALKYL HAS 1 - 2 CARBON ATOMS, STYRYL, P-ALKYLSTYRYL IN WICH THE ALKYL HAS 1 - 3 CARBON ATOMS, P-ALKYLSTYRYL IN WHICH THE ALKYL HAS 1 - 2 CARBON ATOMS, 3,4-DIALKOXYSTYRYL IN WHICH THE ALKYL HAS 1 - 2 CARBON ATOMS, 3,4,5-TRIALKOXYSTYRYL IN WHICH THE ALKYL HAS 1-2 CARBON ATOMS, P - AMINOSTYRYL, P - DIALKYLAMINOSTYRYL IN WHICH THE ALKYL HAS 1 - 4 CARBON ATOMS, P-NITROSTYRYL, P - HALOGENOSTYRYL, 2 - (A-PYRROLY) ETHENYL, 2-(A-THIENYL) ETHENYL, 2-(B-INDOLYL)ETHENYL, 2-(A-FURYL)ETHENYL AND 2(4&#39;&#39;-ALKOXYNAPHTHYL)ETHENYL IN WHICH THE ALKYL HAS 1-2 CARBON ATOMS AND 2-(1-NAPHTHYL)ETHENYL, AND A- IS AN ANION FUNCTIONAL GROUP, AND THEIR USE AS A SENSITIZER FOR ORGANIC PHOTOCONDUCTORS.

Aug. 27, 1974 SUBSTITUTED NAPHTHO 2 {1-61 PYRYLIUB PERCHLORATE'S Filed Dec. 26. 1971 2 Sheets-Sheet 1 l I I l l l l l I l l l 3600 2800 2000 I800 I600 I400 I200 I000 800 600 400 WAVE LENGTH (m FIG. 2

IIIIIIIII III I I I IIIIIIIIIIIIIIIIIII 3600' 23'00 I 2600 I000 I000 I400 I200 I000 800 600 400 4000 WAVE LENGTH (mm FIG. 3

|OO1. LIIIIIII|I IIIIIIIIIIIIIIIIIIIIIIIII: I

l l l l l l I d8 S I800 I600I4OO I200 I000 800 600 400 WAVE LENGTH (my) SHOJI MARUYAMA ETAL' 3,832,349

Aug. 27, 1914 H JI MARUYAMA ETAL 3,832,349

SUBSTITUTED NAPHTHO[2,1-BJ'PYRYLIUI PERCHLORA'PES Filed Dec. 26. 1971 2 Sheets-Sheet ,2

2 I: m z LL! w 700 600 500 400 /WAVE LENGTH (mm FIG. 5

SENSITIVITY United States Patent Office 3,832,349 Patented Aug. 27, 1974 US. Cl. 260-240 D 4 Claims ABSTRACT OF THE DISCLOSURE Naphthopyrylium salts represented by the formula (I):

wherein R is selected from the group consisting of, palkylstyryl in which the alkyl has 1 3 carbon atoms, p-alkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4-dialkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4,5-trialkoxystyryl in which the alkyl has 1-2 carbon atoms, p-dialkylaminostyryl in which the alkyl has 1-4 carbon atoms, p-nitrostyryl, p-halogenostyryl, p-carboxystyryl; R is selected from the group consisting of, p-alkoxyphenyl in which the alkyl has 1 2 carbon atoms, styryl, p-alkylstyryl in which the alkyl has 1 3 carbon atoms, p-alkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4-dialkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4,S-trialkoxystyryl in which the alkyl has 1-2 carbon atoms, p aminostyryl, p dialkylaminostyryl in which the alkyl has 1 4 carbon atoms, p-nitrostyryl, p halogenostyryl, 2 (a pyrrolyl)ethenyl, Z-(a-thienyl) ethenyl, Z-(fl-indolyDethenyl, 2-(a-furyl)ethenyl and 2- (4'-alkoxynaphthyl)ethenyl in which the alkyl has 1-2 carbon atoms and 2-(l-naphthyl)ethenyl, and A is an anion functional group, and their use as a sensitizer for organic photoconductors.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to naphthopyrylium salts and their use as electrophotographic sensitizers.

2. Description of the Prior Art Various kinds of organic photoconductors have been developed for electrophotographic copy materials. Organic photoconductors are superior to inorganic photoconductors in transparency, flexibility and film forming ability and can readily form a uniform, transparent and often almost colorless photosensitive layer on a support. On the other hand, however, their light sensitivity is very low compared with inorganic photoconductors such as zinc oxide, selenium and the like, so the aforementioned merits are not realized fully in the practical uses. Since the light sensitivity of photoconductors themselves is generally low, it is a widely accepted practice to add light sensitive substances to them if the peak of their sensitivity is in the short wavelength region of the visible spectrum, so that the sensitivity might be shifted to the long wavelength region of the spectrum. Many organic substances are known as sensitizers; however, none of them are entirely satisfactory. Crystal Violet and Methylene Blue are representative organic sensitizers and they must be used in great quantity to achieve satisfactory sensitivity. Such excessive use of these sensitizers presents a problem of coloring the copy material or copy excessively.

SUMMARY OF THE INVENTION The present invention provides naphthopyrylium salts represented by the formula (I) wherein R is selected from the group consisting of, p-alkylstyryl in which the alkyl has 1-3 carbon atoms, p-alkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4-dialkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4,5-trialkoxystyryl in which the alkyl has 1-2 carbon atoms, p'dial-kylaminostyryl in which the alkyl has l- 4 carbon atoms, p-nitrostyryl, p-halogenostyryl, p-carboxystyryl; R is selected from the group consisting of, p-alkoxyphenyl in which the alkyl has 1 2 carbon atoms, styryl, p-alkylstyryl in which the alkyl has l-3 carbon atoms, p-alkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4-dialkoxystyryl in which the alkyl has 1 2 carbon atoms, 3,4,5-trialkoxystyryl in which the alkyl has 1 2 carbon atoms, p-aminostyryl, p-dialkylaminostyryl in which the alkyl has 1 4 carbon atoms, pnitrostyryl, p-halogenostyryl, 2-(a-pyrrolyl)ethenyl, 2- (a-thienyDethenyl, 2 (B-indolyDethenyl, 2 (a-furyl)- ethenyl and 2-(4'-alkoxynaphthyl)ethenyl in which the alkyl has 1 2 carbon atoms and 2-(1-naphthyl)ethenyl, and A- is an anion functional group.

Further this invention provides sensitizers, which consists of said naphthopyrylium salts, for use in electrophotographic copy materials with the object of solving the aforementioned problems inherent to the copy materials.

These naphthopyrylium salts are novel crystalline substances having a violet or reddish violet or bluish violetcolor. It has been proved that they are useful as optical sensitizers particularly for organic photoconductors used with electrophotographic copy materials.

The naphthopyrylium salts (I) according to the present invention are prepared by either a) reacting Z-hydroxy-lnaphthoaldehyde with a ketone represented by the formula (H) R CH COR (wherein R is selected from the group consisting of hydrogen, alkyl having 1 9 carbon atoms, benzyl, alkoxystyryl in which the alkyl has 1 2 carbon atoms, phenyl and styryl, and R is selected from the group consisting of methyl and phenyl) at a temperature of 15 35C in the presence of a mineral acid; and then adding to the reaction product an acid or its salt having a desired anion functional group, or 1)) further reacting the said reaction product (of Z-hydroxy-l-naphthoaldehyde and the ketone represented by the formula (II)) with an aldehyde represented by the formula (III):

R CHO (wherein R is selected from the group consisting of phenyl, p-alkoxyphenyl in which the alkyl has 1 2 carbon atoms, 3,4-dialkoxyphenyl in which the alkyl has 1 2 carbon atoms, 3,4,5-trialkoxyphenyl in which the alkyl has 1-2 carbon atoms, p aminophenyl, p dialkylaminophenyl in which the alkyl has 1-4 carbon atoms, p-nitrophenyl, p-halogenophenyl, naphthyl, 4-alkoxynaphthyl in which the alkyl has 1-2 carbon atoms, pyrrolyl, thienyl, indolyl and furyl) at a temperature of 15- 35 C; and then adding said acid or its salt having an anion functional group.

2-hydroxy-l-naphthoaldehyde, the ketone which is expressed by the formula (II) and the aldehyde of which is expressed by the formula (III), can be readily synthesized according to known methods, and are available on the market.

In the methods of (a) and (b) according to the present invention, an organic solvent such as alcohol, dioxane or tetrahydrofuran which is capable of dissolving the materials may be used singly or in combination. Preferably an admixture of such organic acids as formic acid and/ or acetic acid added thereto. Further, the presence of a mineral acid as a condensating agent, especially hydrochloric acid, in the range of about -20 moles per mole of the aldehyde is preferable. It is also advisable to complete the reaction by further adding about -20 moles of a mineral acid based on one mole of the aldehyde. A satisfactory result will be obtained when the over-all reaction temperature is controlled between and 35 C.

In the methods of (a) and (b), the anion functional group A can be easily introduced due to salt-formation reaction and any of the acids or their salts having an anion functional group such as BF4 C10 1 CSN', AuCl and C1- are applicable.

In the foregoing method a), the molar ratio of 2- hydroxynaphthoaldehyde to the ketone represented by the formula (II) is 1:1, while in the foregoing method b), the molar ratio of the reaction product (of 2-hydroxy-lnaphthoaldehyde with the ketone (II)) to the aldehyde represented by the formula (III) is 1:2 in the case of R being methyl and 1:1 in the case of R being a radical other than methyl, respectively.

The naphthopyrylium salts thus obtained can be used as sensitizers for such widely known organic photoconductors as polyvinylcarbazole, its derivatives, and polyvinylanthracene. In this case, the proper quantity of the sensitizer is 0.01-2 wt. percent of the organic photoconductor and the sensitizer may be added to the photoconductor in solid form, or more preferably after having been dissolved in a solvent. Further, if required, a resin such as polycarbonate can be added as a resinous binder.

Representative derivatives of naphthopyrylium salts which are prepared in accordance with the present invention are listed hereunder:

Compound No.

1 2-(p-methoxystyryl)-3-phenylnaphthopyrylium perchlorate 2: 2-(4'-rnethoxynaphthostyryl)-3-phenylnaphthopyrylium perchlorate 3 2-(3,4'-dimethoxystyryl)-3phenylnaphthopyrylium perchlorate 4: 2- 3 ',4'-diethoxystyryl) 3 -phenylnaphthopyrylium perchlorate 5 2- (p-ethoxystyryl) 3 -phenylnaphthopyrylium,

perchlorate 6: 2-(fi-2'-thiophene ethenyl)-3-phenylnaphthopyrylium perchlorate 7: 2- B-2-pyrrole ethenyl) -3-phenylnaphthopyrylium prechlorate 8: 2-(/3-3'-indole ethenyl)-3-phenylnaphthopyrrylium perchlorate 9: 2- (p-methoxystyryl) -3-isopropylnaphthopyry1ium perchlorate 10: 2- (p-methoxystyryl) -3-hexylnaphthopyrylium perchlorate 11: 2,3-di(p-methoxystyryl) naphthopyrylium perchlorate 12: 2-(p-methoxystyryl) naphthopyrylium perchlorate 13: 2,3-di(p-dimethylaminostyryl) naphthopyrylium perchlorate These compounds are [2,1-b] compounds and can also be named in accordance with the system utilized in the examples.

BRIEF DESCRIPTION OF THE DRAWINGS In FIG. 1, FIG. 2 and FIG. 3, the respective curves show the infrared absorption spectra of the derivatives of the naphthopyrylium salt obtained according to the present invention.

FIGS. 4 and FIG. 5 show the spectral sensitivity of the polymeric compounds admixed with the sensitizer comprising the naphthopyrylium salt prepared in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 Preparation of 2-(p-methoxystyryl)-3-phenylnaphtho [2, l-b pyrylium perchlorate /CH; C

1 g. of 2-hydroxy-l-naphthoaldehyde and 0.7 g. of isobutyl ketone [(CH CHCH COCH were dissolved in the mixed solvent consisting of 40 ml. of alcohol and 20 ml. of formic acid, to which was added 5 ml. of undiluted hydrochloric acid at a room temperature and the solution was left standing for 12 hours. After that, a solution prepared by dissolving 1.3 g. of p-methoxybenzaldehyde [o HC-Q-O 0 Ha in 20 ml. of formic acid, to which was added 5 ml. of 35% hydrochloric acid, and the solution was left standing overnight. The reaction product was then poured into the cold aqueous solution of 10% perchloric acid. The separated product was filtrated and was subjected to recrystallization by use of acetic acid and 2.5 g. of the desired product was obtained. The crystal had a reddish violet color and showed the melting point of -187 C.

The results of the elemental analysis conducted on the product (as C H ClO were as follows:

theoretical values: C; 66.0%, H; 5.0% experimental values: C; 66.3%, H; 4.93%

The absorption maximum wave length was found to be 540 m and 600 m and the molar extinction coeflicients (6) were 22x10 and 12x10 when measured with the product after having been dissolved in 1,2-dichloroethane. Its infrared absorption spectrum was as shown in FIG. 1.

Example 2 Preparation of 2,3-di-(p-methoxystyryl) naphtho[2,1-b] pyrylium perchlorate 6 CH=CHOCH= WonwnQ-oom 1 g. of 2-hydroxy-l-naphthoaldehyde and 0.7 g. of methylethyl ketone [CH CH C0CH were dissolved in the mixed solvent consisting of 10 ml. of tetrahydrofuran and 10 ml. of formic acid, to which solution was added 5 ml. of 35% hydrochloric acid at room temperature and the solution was left standing overnight. A solution prepared by dissolving 2.5 g. of p-methoxybenzaldehyde in ml. of formic acid was added thereto, and further 5 m1. of 35% hydrochloric acid was added and the solution was kept standing overnight. The succeeding procedures were taken according to Example 1 to obtain 2.5 g. of the desired crystalline product of violet color having the melting point of 235237 C.

The results of the elemental analysis (as c31H23C1O7) were as follows:

theoretical values: C; 68.31%, H; 4.58% experimental values: C; 68.96%, H; 4.48%

When this crystal was dissolved in 1,2-dichloroethane, it was confirmed that the absorption maximum wave length (x was in 597 mp. and the molar extinction coefficient (5) was 2.5 10 The infrared absorption spectrum was as shown in FIG. 2.

Example 3 Preparation of 2-[2'-(u-pyrryl)-ethenyl]-3-phenylnaphtho[2,l-b]pyrylium perchlorate 2 g. of 2-hydroxy-l-naphthoaldehyde and 2 g. of

phenylacetone [Gonzo 0cm] were dissolved in the mixture of m1. of dioxane and 15 ml. of formic acid, to which solution was added 6 ml. of 35% hydrochloric acid at a room temperature. Two hours later, a solution prepared by dissolving 2 g. of apirrolylaldehyde L J CHO in 10 ml. of formic acid. Another 5 ml. of 35 hydrochloric acid was added thereto and the solution was left Example 4 Preparation of 2-(3',4'-diethoxystyryl)-2-phenylnaphtho [2,1-b1pyrylium perchlorate OCzHs o l on=on-0oun 2 g. of Z-hydroxy-l-naphthoaldehyde and 2 g. of phenylacetone [Q-omooom] were dissolved in the mixed solvent consisting of 20 m1. of dioxane and 15 ml. of formic acid, to which admixture was further added 6 ml. of 35% hydrochloric acid. After the mixture was stirred for the period of two hours, a solution prepared by dissolving 2 g. of 3,4-diethoxybenzaldehyde in 5 ml. of formic acid and another 5 ml. of 35 hydrochloric acid was added thereto. The mixture was kept standing at a room temperature overnight. The same procedures as in Example 1 followed and 4.5 g. of the desired crystalline product of reddish violet color having the melting point of -187 C. was obtained.

The results of the elemental analysis (as C31H2I7C1O7) were as follows:

theoretical values: C; 68.0%, H; 4.94% experimental values: C; 68.88%, H; 4.72%

When the crystalline product was dissolved in 1,2-dichloroethane, the absorption maximum wave length (A was in 613 mg and the molar extinction coefiicient (e) was 5.7 10

Example 5 Preparation of 2- 3- (4'-methoxynaphthyl)ethenyl]-2- phenylnaphtho[2,1-b]pyrylium perchlorate 2 g. of 2-hydroxyl-l-naphthoaldehyde and 2 g. of phenylacetone were dissolved in the mixed solvent consisting of 10 ml. of dioxane and 15 ml. of formic acid, to which solution 5 ml. of 35% hydrochloric acid Was added at a room temperature. The solution was left standing at a room temperature for three hours. A solution prepared by dissolving 2 g. of 4-methoxy-1-naphthoin 15 ml. of formic acid was added to the preceding solution and another 10 ml. of 35% hydrochloric acid was added thereto. The succeeding procedures were taken according to Example 4 and 4 g. of desired crystalline product of bluish violet color having the melting point of 185 C. was obtained.

The results of the elemental analysis (as C I-I ClO were as follows:

theoretical values: C; 71.30%, H; 4.27% experimental values: C; 72.00%, H; 4.50%

With the crystalline product dissolved in 1,2-dichloroethane, the absorption maximum wave length (x was in 660 m and the molar extinction coefficient (e) was 3.1 10

Example 6 Preparation of 2- (p-methoxystyryl)-3-phenylnaphtho- [2, l-b] pyrylium perchlorate 6 when-Goon.

2 g. of Z-hydroxyl- 1 -naphthoaldehyde and 2 g. of phenylacetone were dissolved in the mixed solvent consisting of 20 ml. of dioxane and 15 ml. of formic acid. 6 ml. of 35 hydrochloric acid was added to the solution. Two hours later, a solution of 2 g. of p-anisaldehyde in 5 ml. of formic acid was added to the preceding solution and again 6 ml. of 35% hydrochloric acid was added thereto. Then the solution was kept standing at a room temperature for a whole day and night. The solution was pured in the cooled aqueous solution of 15% perchloric acid and the product thus separated was filtrated and was recrystallized from acetic acid to obtain 1.5 g. of the desired crystalline product of reddish purple color having the melting point of 154 C.

The results of the elemental analysis (as C H ClO were as below:

theoretical values: C; 68.78%, H; 4.29% experimental values: C; 69.41%, H; 4.27%

When measured with the crystal product dissolved in 1,2-dichloroethane, the absorption maximum wave length (x was in 5 86 m and the molar extinction coefficient (6) was 70x10.

Example 7 23 g. of chlorinated polyvinyl carbazole (containing 0.5 chloro per car-bazole ring) and 0.7 g. of polycarbonate resin were dissolved respectively in 33 g. of monochlorobenzene and 6.3 g. of dichloroethane, to which solution 0.5 g. of diphenyl chloride was added to prepare a liquid photosensitive material. A dichloroethane solution was prepared by dissolving in it the aforementioned Compound No. 1 in such a way as to make 5X10- mol/g. (on chlorinated polyvinyl carbazole) solution. After having been mixed thoroughly, the solution was applied to the surface of a sheet of processed paper to form a coating of 56,u. thickness after drying. A copying paper was thus prepared. After having been kept standing overnight, the copying paper was impressed with a positive electric charge by means of the corona discharge of approximately 6 kv. according to a usual method. The copying paper was then subjected to the exposure of the original image for the period of 24 seconds according to the reflective :projection method wherein glow lamps were used for the light source with the illuminance of 20 luxes on the surface of the sensitive coating of the copying paper. The copying paper thus exposed was developed with a liquid developer and the original image was reproduced on the copying paper with fidelity.

Example 8 of of 2.3 g. of brominated polyvinyl carbazole and 0.7 g. polycarbonate resin were solved respectively in 33 g. monochlorobenzene and 6.3 g. of dichloroethane, to which solution was added 0.5 g. of diphenyl chloride to prepared a liquid photosensitive material. A dichloroethane solution was prepared by dissolving in it the aforementioned Compound No. 2 in such a way as to make 5 10- mol/ g. (on brominated polyvinyl carbazole) solution. After having been mixed thoroughly, the same procedures as Example 7 were followed to obtain an image reproduced on the copying paper perfectly true to the original image.

The optimum exposure(lux/second) for obtaining the image to be reproduced on the copying paper is given in the following table:

Norn.)\mx was actually measured with the dichloroothane solution;

FIG. 4 shows the spectral sensitivity curve obtained with copying paper sensitized by use of Compound No. 9 and the light sensitive wave length region extends over the visible wave length region of 470 640 my. FIG. 5 shows a similar curve obtained with copying paper sensitized by use of Compond No. 11 and the light sensitive wave length region extends over the visible wave length region of 490-670 m What we claim is:

1. 2,3 di(p methoxystyryl)naphtho[2,1 b]pyrylium perchlorate.

2. 3 [2' (a-pyrryD-ethenyl]-2-phenylnaphtho[2,1-b]- pyrylium perchlorate.

3. 3 (3,4 diethoxystyryl) 2-pheny1naphth0[2,1-b]- pyrylium perchlorate.

4. 3-[ 3-(4'-methoxynaphthyl)ethenyl] 2 phenylnaphtho [2, l-b pyrylium perchlorate.

References Cited FOREIGN PATENTS 913,482 12/1962 Great Britain 260240 D 1,539,954 8/1968 France 260--240D OTHER REFERENCES CA. 74: 133060u (1971), Contois et al.

CA. 66: 949452 (1967), Nesmeyauov et al.

Indian J. Chem. 7: 2830 (1969), Muljiani et al.

Tetrahedron (1965), 21: 12634270, Boyd et al.

Tetrahedron (1968), 24: 5029-5040, Schiele et al.

Chemical Abstracts 6th Collective Index, 1957-61, p. 7666s.

HENRY R. IILES, Primary Examiner S. D. WINTERS, Assistant Examiner US. Cl. X.R. 

